A Virtual Machine (VM) is an environment, usually a program or operating system, that does not physically exist but is created within another environment. In this context, the VM is called a “guest” while the environment it runs within is called a “host”. Virtual machines can be created to execute an instruction set different than that of the host environment. One host environment (e.g., computer system) can run multiple virtual machines simultaneously. Since virtual machines are separated from the physical resources they use (i.e., memory, CPU cycles), the host environment is often able to dynamically assign those resources among them.